Chronic exercise reduces sympathetic nerve activity in rabbits with pacing-induced heart failure: A role for angiotensin II

BACKGROUND

Chronic exercise (EX) improves the quality of life and increases the survival of patients with chronic heart failure (CHF). Because sympathetic nerve activity is elevated in the CHF state, it is possible that EX is beneficial in this disease due to a decrease in sympathetic outflow.

METHODS AND RESULTS

We evaluated arterial baroreflex function and resting renal sympathetic nerve activity (RSNA) in EX normal and CHF rabbits before and after angiotensin II type 1 (AT(1)) receptor blockade. Four groups of rabbits were studied: a normal non-EX group, a normal EX group, a CHF non-EX group, and a CHF EX group. EX lowered resting RSNA in rabbits with CHF but not in normal rabbits. In addition, EX increased arterial baroreflex sensitivity in the CHF group (heart rate slope: CHF 1. 7+/-0.3 bpm/mm Hg, EX CHF 4.9+/-0.3 bpm/mm Hg; P:<0.01; RSNA slope: CHF 2.2+/-0.2%max/mm Hg, EX CHF 5.7+/-0.4%max/mm Hg; P:<0.01. AT(1) receptor blockade enhanced baroreflex sensitivity in the non-EX CHF rabbits but had no effect in EX CHF rabbits. Concomitant with this effect, EX lowered the elevated plasma angiotensin II concentration in the CHF group. A significant positive correlation was observed between sympathetic nerve activity and plasma angiotensin II.

CONCLUSIONS

These data strongly suggest that EX reduces the sympathoexcitatory state in the setting of CHF. Enhanced arterial baroreflex sensitivity may contribute to this reduction. In addition, EX lowers plasma angiotensin II concentration in CHF. These data further suggest that the lowering of angiotensin II may contribute to the decrease in sympathetic nerve activity after EX in the CHF state.

Early referral, diagnosis, and treatment of rheumatoid arthritis: evidence for changing medical practice

OBJECTIVES

To study the delay in starting disease modifying anti-rheumatic drugs (DMARDs) in patients with rheumatoid arthritis (RA), and any changes in medical practice between 1980 and 1997.

METHODS

198 consecutive RA patients attending the rheumatology clinics at a teaching hospital, for routine review, had their case sheet reviewed. The dates of symptom onset, general practitioner (GP) referral, first clinic appointment and first use of DMARD were recorded. Data were collected on the erythrocyte sedimentation rate, C reactive protein, rheumatoid factor, and the presence/absence of erosions at the first clinic assessment. Patients were split into four groups according to the date of their first clinic assessment-before 1986, 1987-9, 1990-3, and 1994-7.

RESULTS

There was a sharp drop in the delay between symptom onset and GP referral (before 1986, 21 months; 1987-89, 23 months; 1990-3, 7 months; 1994-7, 4 months, p<0.03), and in the delay between first assessment at the rheumatology clinic and the start of DMARD treatment (before 1986, 32 months; 1987-89, 21 months; 1990-1993, 8 months; 1994-7, 1 month, p<0.001). The number of patients given DMARD treatment within six months of symptom onset increased from 5% (before 1994) to 44% (1994-7). Seventy three per cent of patients waiting more than a year from symptom onset to first clinic appointment already had erosive change, compared with 34% of patients seen within a year.

CONCLUSIONS

Patients are being referred earlier in their disease, and DMARDs are prescribed sooner in the disease course. There has been a substantial increase in the proportion of patients treated with a DMARD within six months of symptom onset.

On the cellular mechanisms by which the bicarbonate ion mediates the extragenomic action of progesterone on human spermatozoa

Progesterone exerts an extragenomic action on human spermatozoa, inducing a rapid calcium transient in the acrosomal domain of these cells and enhancing their potential for fertilization. This response is known to exhibit an absolute dependence on the presence of extracellular bicarbonate, although the mechanisms underlying this interaction are not understood. In this study, bicarbonate was found to exert a dose-dependent impact on the ability of progesterone to promote sperm-oocyte fusion in the absence of any collateral effect on sperm motility. The loss of sperm function in bicarbonate-free medium was associated with a failure to produce reactive oxygen species, an impaired capacity to exhibit redox-associated changes in tyrosine phosphorylation, and an apparent incapacity to generate normal calcium transients on exposure to progesterone. These defects were not related to a cAMP deficiency but were associated with a significant fall in intracellular pH. If cytosolic pH was chemically buffered into the normal range, then the spermatozoa regained every element of their response to progesterone. These results emphasize the importance of an alkaline intracellular milieu for the extragenomic action of progesterone on human spermatozoa and stress the fundamental difference between intracellular and extracellular sources of bicarbonate in maintaining the proton balance within such cells.

Reactive oxygen species generation by human spermatozoa is induced by exogenous NADPH and inhibited by the flavoprotein inhibitors diphenylene iodonium and quinacrine

Human spermatozoa possess a specialized capacity to generate reactive oxygen species (ROS) that is thought to be of significance in the redox regulation of sperm capacitation (De Lamirande and Gagnon, 1993; Aitken et al., 1995). However, the mechanisms by which ROS are generated by these cells are not understood. In this study we have examined the possible significance of NADPH as a substrate for ROS production by human spermatozoa. Addition of NADPH to viable populations of motile spermatozoa induced a sudden dose-dependent increase in the rate of superoxide generation via mechanisms that could not be disrupted by inhibitors of the mitochondrial electron transport chain (antimycin A, rotenone, carbonyl cyanide m-chlorophenylhydrazone [CCCP], and sodium azide), diaphorase (dicoumarol) xanthine oxidase (allopurinol), or lactic acid dehydrogenase (sodium oxamate). However, NADPH-induced ROS generation could be stimulated by permeabilization and was negatively correlated with sperm function. Both NADH and NADPH were active electron donors in this system, while NAD+ and NADP+ exhibited little activity. Stereo-specificity was evident in the response in that only the beta-isomer of NADPH supported superoxide production. The involvement of a flavoprotein in the electron transfer process was indicated by the high sensitivity of the oxidase to inhibition by diphenylene iodonium and quinacrine. These results indicate that NAD(P)H can serve as an electron donor for superoxide generation by human spermatozoa and present a simple strategy for the production of motile populations of free radical generating cells with which to study the significance of these molecules in the control of normal and pathological sperm function.

Homeobox genes in the Ctenophora: identification of paired-type and Hox homologues in the atentaculate ctenophore, Beroë ovata

Homeobox-containing genes are a phylogenetically widespread family of transcription factors that can regulate cell fates during embryogenesis. Two distinct homeobox gene sequences are described for the atentaculate ctenophore Beroë, the first homeoboxes to be identified in this phylum. Beroë homeobox fragments were cloned in a survey of genomic DNA using polymerase chain reaction (PCR). Parsimony, neighbor-joining, and maximum likelihood methods were used to infer the orthology of the ctenophore sequences to specific homeoboxes from higher metazoans including Drosophila, Caenorhabditis elegans, and humans. Cteno-paired appears most closely related to paired-typed homeoboxes. This is the first evidence of a paired-type homeobox in one of the so-called diploblastic animals. Cteno-Hoxl appears most closely related to members of the Hox class, particularly Antennapedia.

Evidence of deteriorating semen quality in the United Kingdom: birth cohort study in 577 men in Scotland over 11 years

OBJECTIVE

To determine whether the quality of semen has changed in a group of over 500 Scottish men born between 1951 and 1973.

DESIGN

Retrospective review of data on semen quality collected in a single laboratory over 11 years and according to World Health Organisation guidelines.

SETTING

Programme of gamete biology research funded by Medical Research Council.

SUBJECTS

577 volunteer semen donors. Of these, 171 were born before 1959, 120 were born in 1960-4, 171 in 1965-9, and 115 in 1970-4.

MAIN OUTCOME MEASURES

Conventional criteria of semen quality including semen volume (ml), sperm concentration (10(6)/ml), overall motility (% motile), total number of sperm in the ejaculate (10(6)), and total number of motile sperm in the ejaculate (10(6)).

RESULTS

When the four birth cohort groups were compared a later year of birth was associated with a lower sperm concentration, a lower total number of sperm in the ejaculate, and a lower number of motile sperm in the ejaculate. The median sperm concentration fell from 98x10(6)/ml among donors born before 1959 to 78x10(6)/ml among donors born after 1970 (P=0.002). The total number of sperm in the ejaculate fell from 301x10(6) to 214x10(6) (P=0.0005), and the total number of motile sperm in the ejaculate fell from 169.7x10(6) to 129.0x10(6) (P=0.0065).

CONCLUSION

This study provides direct evidence that semen quality is deteriorating, with a later year of birth being significantly associated with a reduced number of sperm in adult life.

Prospective study of 210 consecutive cases of endocapsular phacoemulsification using the AMO SI-30NB 3-piece foldable lens

PURPOSE

To assess the acceptability of clinical outcome achieved with use of the SI-30NB lens, as well as the incidence of any lens related complications.

METHODS

This prospective study evaluated 210 consecutive eyes undergoing endocapsular phacoemulsification cataract surgery (EPECS), with implantation of the AMO SI-30NB foldable three-piece lens, commencing with the first patient in our practice receiving this implant. There was 99% follow-up for at least three months, with a mean of nine months, and a range of three to 14 months. Incisions were a maximum of 3.2 mm in size, and this allowed minimisation of astigmatism, and maximisation of early visual rehabilitation.

RESULTS

The final visual acuity results were excellent, with 95% of cases achieving corrected vision of 6/12 or better. All cases without pre-existing ocular pathology achieved corrected vision of 6/6, apart from a single case which achieved 6/9, but the patient died before follow-up. The lens-related complication rate was less than 1% (two patients). No decentration of any other implant occurred, and no patient complained of edge glare. There were no cases of iris chafing or pigment dispersion. Only three patients (1.4%) required Yag posterior capsulotomy in the first 14 months of the study. Central bag-bag fixation was achieved in 206 of the 210 cases in the study (98%).

CONCLUSION

The results achieved using the SI-30NB lens with a small incision phaco procedure were excellent. Lens-related complications occurred in only two cases and very few cases have had problems with posterior capsular opacification.

Ketamine inhibits glutamate-, N-methyl-D-aspartate-, and quisqualate-stimulated cGMP production in cultured cerebral neurons

BACKGROUND

Glutamatergic signaling has been linked to the recently discovered neurotransmitter/neuromodulator nitric oxide (NO), and several classes of anesthetics block some step in glutamatergic signaling. This study was designed to determine whether or not ketamine would prevent NO-dependent cGMP production stimulated by glutamate (GLU) and the GLU analogs NMDA, quisqualate (QUIS), and kainate (KAIN).

METHODS

Primary cultures of cortical neurons and glia (prepared from 16-day gestational rat fetuses) were used after 12-16 days in culture. Reactions were carried out in magnesium-free buffer containing 100 microM 3-isobutyl-1-methylxanthine, and cGMP content of cultures was used as a bioassay of NO production.

RESULTS

Cyclic GMP production stimulated by sodium nitroprusside (100 microM) occurred predominately in neurons and not in glia. Neurons were spontaneously active in these cultures; basal cGMP production was decreased by 50% in the presence of 1 microM tetrodotoxin (TTX). Glutamate (100 microM), NMDA (100 microM), QUIS (300 microM), and KAIN (100 microM) each increased cGMP content of neuronal cultures. L-NMMA (100 microM), a NO synthase inhibitor, prevented the stimulation of cGMP production by GLU or its analogs. Pretreatment with MK-801 (1 microM) or ketamine (10-100 microM) inhibited GLU-, NMDA-, and QUIS-stimulated cGMP production. Quisqualate-stimulated responses were the most sensitive to inhibition by ketamine and NMDA-stimulated responses were the least sensitive to inhibition. MK-801 and ketamine did not significantly inhibit KAIN-stimulated cGMP production. CNQX (10 microns) blocked KAIN-stimulated cGMP production only.

CONCLUSIONS

The authors' data demonstrate that ketamine inhibited NO synthesis stimulated by NMDA- and non-NMDA-receptor specific analogs. Our findings indicate that blockade of QUIS- as well as NMDA-subtypes of GLU- receptor may be important in the development of ketamine-induced anesthesia.

The entropion patch: a method of temporarily correcting involutional entropion with adhesive tape

A simply designed entropion patch provided effective temporary preoperative relief of the symptoms of lid malposition in lower lid involutional entropion in six patients. The patch is easily fashioned and used after appropriate instruction, with its design taking into account lid mechanics and the pathophysiology of involutional entropion.

Prospective evaluation of one surgeon's first 100 cases of endocapsular phacoemulsification cataract surgery

In this series of one surgeon's first 100 cases of endocapsular phacoemulsification cataract surgery (EPECS), believed to be the first truly prospective study of its kind, 86% of patients achieved corrected vision of 6/6 to 6/4; 96% achieved vision of 6/12 or better; and excluding those with pre-existing pathology, 99% achieved 6/12. Posterior capsular rupture occurred in 11 cases, with vitrectomy being required in eight cases. Detailed analysis of the 100 cases is provided.

Prospective study of short and ultrashort regimens of gonadotropin-releasing hormone agonist in an in vitro fertilization program

OBJECTIVE

To assess the usefulness of the ultrashort regimen of gonadotropin-releasing hormone agonist (GnRH-a) in ovulation induction in an in vitro fertilization (IVF) program.

DESIGN

A prospective randomized trial comparing short and ultrashort regimens of GnRH-a.

SETTING

Aberdeen Assisted Reproduction Unit.

PATIENTS

Forty-eight patients having IVF for the first time were randomized between the two protocols.

MAIN OUTCOME MEASURES

Response to ovarian stimulation and occurrence of spontaneous luteinizing hormone (LH) surges.

RESULTS

In ovulation induction, fertilization, and pregnancy rates the ultrashort regimen produces results that were no different to the short regimen but it did not always prevent an LH surge.

CONCLUSION

The ultrashort regimen can be a useful alternative for ovarian stimulation of patients undergoing IVF.

Mothers' concepts of normality, behavioural change and illness in their children

Several sociological models have been put forward to explain illness behaviour. However, little research has examined general practitioners' understanding of mothers' perceptions of their children's health and illness. The aim of this study was to attempt to understand the cultural context of children's illness. Mothers' concerns about their children's health and illnesses were examined by describing the mothers' own perceptions of alterations in their children's behaviour. The mothers' perceptions of normality appeared to underpin their negotiation of illness. The concept of normality was found to change over time, to be uniquely based on individual experience, to be related to health, and to a process of normalization. The mothers' perceived importance of children's behavioural changes are discussed: they may be precursors or results of illness, causes for concern in their own right, or a management problem for the household. Identifying and acknowledging the unique way in which mothers perceive health and illness in their children may lead to enhanced understanding and satisfaction for both the general practitioner and mother in the consultation process.

Vascular injuries caused by anti-personnel mines

During a 3 month period 94 patients, injured by anti-personnel mines on the Thailand-Cambodian border, underwent emergency surgical treatment in the ICRC (International Committee of the Red Cross) hospital in Khao-I-Dang, Thailand. As a result of difficult evacuation facilities at the border, the mean time between injury caused by an anti-personnel mine and admission to the hospital was 8.3 hours (range: 2.5 to 14 hours). However, in 14 patients a penetrating vessel injury was sustained, and these underwent surgical treatment. Peripheral vascular repair was performed in 10 patients. The vessels involved in these reconstructions were: popliteal artery: 4, femoral artery: 2, anterior tibial artery: 3, femoral vein: 1. Vascular repair of the iliac artery and vein was performed in 1 patient. Limb amputation had to be performed in 3 patients, due to the long duration of tourniquet application in these cases. In the field conditions at Khao-I-Dang hospital many surgical facilities normally present in Western hospitals were unavailable. However, our series shows that satisfactory results could be obtained, despite adverse working conditions.